Acute respiratory infections (ARI) result in ~ 1.9 million childhood deaths per year in developing countries, 20% of the deaths are in India. Influenza in young children is as severe as in high-risk adults and frequently goes unrecognized. In the subtropics, influenza is an important cause of hospitalization among children, with rates exceeding those reported for temperate regions. Influenza was found in 15% of the children hospitalized with ARI in India. Among the challenges to the understanding of viral infections in the developing world has been the requirement for diagnostic tools that exceed the available laboratory capacity. An example of this lies in the application of molecular diagnostics such as reverse transcription polymerase chain reaction (RTPCR). While these assays offer advantages for virus detection their use has been limited by cost. Reverse-transcription loop mediated isothermal amplification (LAMP) is a novel technique that can amplify RNA with high specificity, efficiency, rapidity and at a low cost. We propose to develop LAMP assays for use in the study of influenza virus in India. This will entail human and avian influenza virus detection and characterization as to type and subtype. In Aim 1 LAMP assays will be established using human influenza virus and in vitro transcribed RNAs from human and avian influenza target genes. Visual and machine detection systems will be compared. A quantitative LAMP assay for influenza will also be developed. In Aim 2 the LAMP assays will compared to culture and RTPCR for the detection of influenza virus. The samples to be used are from a unique collection of clinical samples available in Delhi, including prospectively collected samples from studies of viral ARI in children and a national influenza virus surveillance network. Quantitative LAMP will be used to test the hypothesis that viral loads correlate with disease severity in children. This application proposes to develop new research technology to address influenza epidemiology and pathogenesis. In addition, it addresses a high-priority influenza research area, the development of sensitive, specific, and rapid clinical diagnostic tests for influenza. Although the emphasis of this proposal is on influenza in India, the results should be broadly applicable, with the potential global use. NARRATIVE The proposed studies are relevant to public health because influenza virus infections are an important cause of disease among children and adults in both developed and developing countries. Improved virus detection methods can improve influenza diagnosis and support studies of antivirals and vaccines against influenza. [unreadable] [unreadable] [unreadable]